ON THEORTHO:PARARATIO OF H+3IN DIFFUSE MOLECULAR CLOUDS

Diffuse Atomic and Molecular Clouds

Diffuse interstellar clouds have long been thought to be relatively devoid of molecules, because of their low densities and high radiation fields. However, in the past ten years or so, a plethora of polyatomic molecules have been observed in diffuse clouds, via their rotational, vibrational, and electronic transitions. In this review, we propose a new systematic classification method for the di...

Extragalactic molecular clouds and chemistry of diffuse interstellar clouds

Zusammenfassung Since the discovery of a cold molecular component of the interstellar medium in the 1970s, it has been realized that most of the dark clouds are actually molecular clouds, consisting mainly of molecular hydrogen and some amount of dust and other molecules. Nowadays, molecular clouds are recognized as places of star-formation in the Milky Way and other galaxies. Therefore, studie...

Non-Thermal Chemistry in Diffuse Clouds with Low Molecular Abundances

High quality archival spectra of interstellar absorption from C I toward 9 stars, taken with the Goddard High Resolution Spectrograph on the Hubble Space Telescope, were analyzed. Our sample was supplemented by two sight lines, 23 Ori and β Sco, for which the C I measurements of Federman, Welty, & Cardelli were used. Directions with known CH absorption, but only upper limits on absorption from ...

Magnetic Fields in Diffuse H I and Molecular Clouds

CN excitation and electron densities in diffuse molecular clouds

Utilizing previous work by the authors on the spin-coupled rotational cross-sections for electron–CN collisions, data for the associated rate coefficients are presented. Data on rotational, fine-structure and hyperfine-structure transition involving rotational levels up to N = 20 are computed for temperatures in the range 10–1000 K. Rates are calculated by combining Born-corrected R-matrix calc...